Process of destroying undesired plants



3,018,175 PROQESS F DESTROYING UNDESIRED PLANTS Margaret D. Cameron, Beaumont, Tern, assignor to Monsanto Chemical tCompany, St. Louis, Mo., 2 corporation of Delaware No Drawing. Original application June 4, 1956, Ser. No. 588,989. Divided and this application Feb. 29, 1960, Ser. No. 11,477

5 Claims. (CI. 71-25) This invention relates to acetylenic ethers and more particularly to tetrahydropyranyl ethers of tertiary acetylenic alcohols, to a process of making the same, and compositions and methods for the application of the novel others as herbicides and as fungicides. This application is a division of co-pending application Serial No. 588,989, filed June 4, 1956.

The novel compounds of this invention are prepared by addition of a tertiary acetylenic alcohol to a dihydropyran compound as illustrated by the following equation:

where R is selected from hydrogen and a lower alkyl radical, B is selected from hydrogen, the carboxaldehyde radical, and lower alkyl or lower alkoxy radicals, R is a lower alkynyl radical, R and R" taken separately are hydrocarbon radicals of from 1 to carbon atoms and free of aliphatic unsaturation and R' and R taken together with the carbon atom to which they are attached represent the carbon atoms necessary to complete a cycloaliphatic nucleus having from 5 to 7 carbon atoms in the cycloaliphatic ring and containing a total of from 5 to 10 carbon atoms, any substituents on the said cycloaliphatic nucleus being alkyl substituents. By aliphatic unsaturation is herein meant carbon-to-carbon, olefinic or acetylenic unsaturation.

It has been known hitherto add primary acetylenic alcohols to dihydropyrans to form tetrahydropyran ethers. In accordance with this invention, there are provided a new and valuable class of acetylenic tetrahydropyranyl ethers wherein the acetylenic radical contains a tertiary carbon atom juxtaposed to the ether oxygen atom. EX- emplary of tertiary acetylenic alcohols which may be used as starting materials for the preparation of others in accordance with this invention are acyclic tertiary alcohols such as 2-methyl-4-pentyn-2-ol, aryl and alkaryl tertiary alcohols such as 1,1-di-p-tolyl-3-butyn-l-ol, cycloaliphatic radicals such as l-(Zpropynyl)cyclohexanol, etc. Particularly preferred in the present process are the tertiary acetylenic alcohols synthesized by the addition of one mole of an acetylene to one mole of a ketone to form an alkynyl carbinol wherein the carbinol carbon atom is alpha to the acetylenically bonded carbon atoms,

as illustrated by the following equation:

' R R RgCECH o=o RzCEC-( J-OH where R represents hydrogen or 'a lower alkyl radical, and R and R" are as defined hereinabove. The class of tertiary acetylenic alcohols of the above formula wherein R and R" represent acyclic hydrocarbon radicals free of aliphatic unsaturation and containing from 1 to 10 carbon atoms, includes, e.g.,

2-methyl-3-butyn-2-ol, 3-methy1-1-pentyn-3-ol,

Patent 0 ice 2 3-ethyl-1-pentyn-3-ol, 3-methyl-1-hexyn-3-ol, 3,4-dimethyl-1-pentyn-3-ol, 3-methyll -heptyn-3-ol, 3,4-dimethyl-1-hexyn-3-ol,

3 ,4,4-trimethyl-1-pentyn-3-ol, 2-rnethyl-3-pentyn-2-ol, 2-methyl-3-heptyn-2-ol, 3-methyl-1-tridecyn-3-ol, etc.

Carbocyclic tertiary acetylenic alcohols which may be added to dihydropyran compounds in accordance with this invention include those wherein at least one of R and R" taken separately represents an aromatic or cycloaliphatic radical, such as 1,l-diphenyl-Z-propyn-l-ol, 2- phenyl-3-butyn-2-ol, 2-cuminyl-3-butyn-2-ol, 1,1-dicycloheXyl-2-propyn-1-ol, etc. The class of carbocyclic tertiary acetylenic alcohols useful in the practice of the present invention also includes the acetylenic alcohols wherein R and R" taken together with the carbon atom to which they are attached represent a cycloaliphatic nucleus having from 5 to 7 carbon atoms in the nucleus and containing a total of from 5 to 10 carbon atoms, any substituents on the said cycloaliphatic nucleus being alkyl radicals. Examples of this class of tertiary acetylenic alcohols are l-ethynylcyclohexanol, l-ethynylcyclopentanol, 1-ethynyl-2-methylcyclohexanol, l-ethynyl'4 methylcyclohexanol, 1-ethynyl-4-isopropylcyclohexanol,

1-( l-propynyl) -4-methylcyc1ohexanol, 1-ethyuyl-4-t-butylcyclohexanol, l-ethynylcycloheptanol, etc.

In accordance with this invention, the tertiary acety lenic alcohol is added to a dihydropyran to form an ether. The presently preferred dihydropyrans are the 3,4-dihydro-ZH-pyrans wherein the oxygen atom of the dihydropyran nucleus is directly linked to an olefinic carbon atom. One readily available class of dihydropyrans conforming to this formula and useful in the process of the invention comprises 3,4-dihydro-2H-pyran and alkyl-3,4-dihydro-2H-pyrans,

e.g., 3-methyl-3,4-dihydro-2H-pyran, 3-ethyl-3,4-dihydro-2H-pyran, 2-methyl-3,4-dihydro-2H-pyran, 3-t-arnyl-3,4-dihydro-2H-pyran, 4-isopropyl-3,4-dihydro-2H-pyran, 2,2-dimethyl-3,4-dihydro-2H-pyran, 2,2,3-trimethyl-3,4-dihydro-2H-pyran, etc.

Another class of dihydropyran compounds amenable to the process of the invention and useful in the preparation of the present novel compounds are the 2-alkoxydihydropyrans, e.g.,

2methoxy-3,4-dihydro-2H-pyran, 2-ethoxy-3,4-dihydro-2H-pyran, 2-isobutoxy-3,4-dihydro-2Hpyran, Z-(Z-methylpentoxy)-3,4-dihydro-2H pyran, etc., as well as the alkyl-2-alkoxydihydropyrans such as 2-methoxy-3ethyl-3,4dihydro-2H-pyran, 2-methoXy-3-isopropyl-3,4-dihydro-2H-pyran, 2-ethoxy-3-ethyl-3,4-dihydro-2H-pyran, 24nethoxy-2-rnethyl-3,4-dihydro-2H-pyran, 2-rnethoxy-2-methyl-3-ethyl-3,4-dihydro-2H-pyran, 2-ethoXy-2,5-diethyl-3,4-dihydro-2H-pyran, 2-methoxy-3,4-dimethyl-3,4-dihydro-2H-pyran, Z-butoxy-S-isobutyl-3,4-dihydro-2H-pyran, etc.

A further available class of dihydropyran compounds which undergo the process of the invention are the dihy- 3 dropyrancarboxaldebydes, which are readily prepared via dimerization of unsaturated aldehydes, e.g., acrolein dimer CH3-C CH! and crotonaldehyde cyclic dimer of the formula H 110 C CHO 25 (H1 OH: H/ CHa The products of the invention are Z-tetrahydropyranyl ethers. A particularly preferred class of such ethers provided by this invention are the tetrahydropyranyl ethers derived from 3,4-dihydro-2H-pyran, wherein each of the R and B substituents in the above formulae represent hydrogen atoms. As examples of the presently provided class of tetra'hydropyranyl ethers with alkynyl tertiary alcohols may be listed, e.g., the products of the reaction of 3,4-dihydro-2H-pyran with acyclic talkynylols such as 2-( 1, l-dimethylpropynyloxy tetrahydropyran,

2-( l-ethy1-l-methylpropynyloxy) tetrahydropyran, 2-(1,l-diethylpropynyloxy)tetrahydropyran,

2- 3methyl-1-hexynyl-3 -oxy) tetrahydropyran,

2- 3,4-dimethyl-1-pentynyl-3-oxy tetrahydropyran, 2-(3-methyl-1-heptynyl-3-oxy) tet-rahydropyran,

2 3 ,4-dimethyll-hexynyl-3-oxy) tetrahydropyran,

2- 3 ,4,4-trirnethyll-pentynyl-3-oxy tetrahydropyran, 2-( 2-rnethyl-3-pentynyl-2-oxy tetrahydropyran, 2-(2-rnethyl-3-heptynyl-2-oxy)tetrahydropyran, etc.

The class of presently provided tetrahydropyranyl ethers of cyclic tertiary acetylenic alcohols includes aromatic acetylenic ethers such as 2-( 1,1-diphenylpropynyloxy)tetrahydropyran,

2-( 2-phenyl-3-butynyl-2-oxy tetrahydropyran,

2- 2-cuminyl-3-butynyl-2-oxy) tetrahydropyran,

2-( 1, l-di-p-tolylpropynyloxy tetrahydropyran, etc.

as well as ethers of cycloalkyl acetylenic tertiary alcohols such as 2-(1,1-dicyclohexylpropynyloxy)tetrahydropyran and 2-( l-ethynylcyclohexyloxy tetrahydropyran,

2-( 1-( l-propynyl cyclohexyloxy tetrahydropyran,

2 l-( 2-propynyl cyclohexyloxy tetrahydropyran,

2-( l-ethynylcycloheptyloxy tetrahydropyran,

2-( 1-ethynyl-4-methylcyclohexyloxy tetrahydropyran, 2-(1-ethynyl-4-t-butylcyclohexyloxy)tetrahydro'pyran, etc.

Also provided by this invention are the ethers of tertiary acetylenic alcohols with alkyl-substituted tetrahydropyrans, such as The compounds obtainable by the addition of tertiary acetylenic alcohols to dihydropyran ethers and alkyldihydropyran ethers are diethers which are alkoxy-alkynyloxytetrahy-dropyrans, and alkoxy-alkyl-alkynyloxy-tetrahydropy-rans. As examples of such tetrahydropyran diethers may be listed the ethers with acyclic tertiary acetylenic alcohols such as 2-methoxy-6-( 1, l-dimethylpropynyloxy) tetrahydropyran,

2 methoxy 3 ethyl 6 (1,1 dimethylpropyny1oxy)- tetrahydropyran,

2 methoxy 3 ethyl 6 (1 methyl 1 ethylpropynyloxy) tetrahydropyran,

2 butoxy 6 (1,1 dimethylpropynyloxy)tetrahydro- 2 ethoxy 3 ethyl 6 (1,1 dimethylpropynyloxy)- tetrahydropyran,

2 methoxy 3 ethyl 6 -(3,4,4 trimethyl 1 pentynyl- 3-oxy) tetrahydropyran,

2 methoxy 3,4,4 trimethyl 6 (2 methyl 4 pentynyl-2-oxy tetrahydropyran,

2 amyloxy 3 arnyl 6 (1,1 dimethylpropynyloxy)- tetrahydropyran, etc.

Examples of such tetrahydropyran diethers wherein the alkynyloxy ether radical contains a cyclic nucleus are, e.g.,

2-methoxy-6-( l, l-diphenylpropynyloxy tetrahydropyran,

2 methoxy 3 ethyl 6 (1,1 di p --tolylpropynyloxy)tetrahydropyran,

2 isobutoxy 3 methyl 6 (1,1 diphenylpropymyloxy)tetrahydropyran,

2-ethoxy-6-( l-ethynylcyclohexyloxy) tetrahydropyran,

2 methoxy 3 ethyl 6 (1 (1 propynyl)cyclohexyloxy)tetrahydropyran,

2 methoxy 3 isopropyl 6 (1 (2 propynyl) 4 methylcyclohexyloxy) tetrahydropyran,

2 methoxy 3 ethyl 6 (l ethynyl 2,4 dimethylcyclohexyloxy)tetrahydropyran, etc.

A further class of compounds provided by this invention are the tetrahydropyrancarboxaldehyde ethers. As examples of the presently aflorded ethers which may be derived from acrolein dimer may be listed, e.g.,

6-( 1, l-dimethylpropynyloxy) tetrahydropyran-Z-carboxaldehyde,

6-( 1,1-diethylpropyny1oxy) tetrahydropynan-Z-carboxaldehyde,

6- (3 ,4-dimethyl-1-pentynyl-3-oxy) tetrahydropyran-Z-carboxaldehyde,

6-( 3-methyll-heptynyl-S-oxy) tetrahydropyran-Z-carboxaldehyde,

6-( 2-methyl-3-pentynyl-2-oxy) tetrahydropyran-Z-carboxaldehyde,

6-( 1,1-diphenylpropynyloxy)tetrahydropyran-2-carboxaldehyde,

6- 2-phenyl-3-butynyl-2 oxy) tetrahydropyran-Z-carboxaldehyde,

6-( l-ethynylcyclohexyloxy) tetrahydropyran-Z-carboxaldehyde,

6-( 1-ethynyl-4-isopropy1cyclohexyloxy)tetrahydropyran- 2-carboxaldehyde,

6-( 1-( l-propynyl cycloheptyloxy) tetrahydr0pyran-2-carboxaldehyde, etc.

Similarly, from methacrolein dimer may be obtained 2,5 -dimethyl-6-( 1,1-dimethylpropynyloxy) tetrahydropyran-2-carboxaldehyde,

2,5-dimethyl-6-( 1 l-diethylpropynyloxy) tetrahydropyran- 2-carboxaldehyde,

2,5-dimethyl-6-( 2-methyl-3 -pentynyl-2-oxy) tetrahydropyran-Z-carboxaldehyde,

2,5 -di1nethyl-6- 3 ,4,4-trimethyl- 1-pentynyl-3-oxy) tetrahydropyran-2-carboxaldehyde,

2,5-dimethyl-6- 2-p-tclyl-3-butynyl-2-oxy) tetrahydropyran-Z-carboxaldehyde,

2,5-dimethyl-6-(1-ethynylcyclohexyloxy)tetrahydropyran- Z-carboxaldehyde,

2,5-dimethyl-6-( l-ethynyl-4-isoamylcyclohexyloxy)tetrahydropyran-Z-carboxaldehyde, etc.

Derivatives obtainable from the cyclic dimer of crotonaldehyde illustrated above include, e.g.,

3,4-dimethyl-6-( 1,1-dimethylpropynyloxy)tetrahydropyran-Z-carboxaldehyde,

3,4-dimethyl-6- 3-methyl-l -heptynyl-3-oxy) tetrahydropyran-2-c arboxaldehyde,

3,4-dirnethyl-6-( l, l-diphenylpropynyloxy) tetrahydropyran-Z-carboxaldehyde,

3,4-dimethyl-6-( l-ethynylcyclohexyloxy) tetrahydropyran- 2-carboxa1dehyde,

3 ,4-dimethyl-6-( 1- l-propynyl -4-methylcyclohexyloxy) tetrahydropyran-Z-carboxaldehyde, etc.

In similar fashion, where the alkoxyand alkyldihydropyran-Z-carboxaldehyde starting materials conforming to the above formula are available, there may be prepared 3- ethyl-S-methoxy 2,5-dimethyl-6-(1,1-dimethylpropynyloxy) tetrahydropyran-Z-carboxaldehyde, 2-methyl-6-( 1,1- diethylpropynyloxy)tetrahydropyran-Z-carboxaldehyde, 3- isobutyl 6-(1,l-di-p-tolylpropynyloxy)tetrahydrQpyran-Z- carboxaldehyde, etc.

In carrying out the preparation of the present ethers, the dihydropyran compound is simply contacted with the tertiary acetylenic alcohol under slightly acid conditions until the action is complete. Preferably, the reactants are contacted in approximately equimolecular amounts, although a slight excess of either component may be used if desired. Large excesses of the alcohol should usually be avoided when the alcohol is being reacted with an all:- oxydihydropyran or dihydropyran carboxaldehyde, to avoid undesired side reactions such as displacement of the alkoxy group or formation of an acetal with the carboxaldehyde group. Solvents or diluents may be used, if desired, but are not generally necessary; examples of suitable solvents which may be used to dilute the reaction mixture are, e.g., benzene, hexane, diethyl ether, dioxane, dichlorobenzene, etc. Generally, the reaction of the alcohol with the dihydropyran compound proceeds readily and is frequently found to be exothermic. If desired, the reaction temperature may be controlled, e.g., by dilution with inert solvents or by cooling; the application of heat to accelerate completion of the reaction is generally unnecessary. Subor superatmospheric pressures may be applied, depending on the temperature conditions of the reaction, but pressure variation is ordinarily without advantages.

The process of the invention is executed in the presence of an acid reacting material. Suitable acids are, e.g., strong mineral acids, acid salts, or organic acids, as well as materials which react in situ to produce acidic conditions. The acidic catalyst desirably is one that is soluble in the reaction mixture, although substantially insoluble acidic materials may be used. Suitable catalysts include, e.g., mineral acids, such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc., acidic salts such as sodium bisulfate, sodium dihydrogen phosphate, aluminum sulfate, etc., and organic acids such as oxalic acid, p-toluenesulfonic acid, and acetic acid. The acidic material need be present only in catalytic amounts, a preferred range being from about 0.10% to about 1% by weight of reactant, though it is not excluded to operate with greater or lesser amounts thereof.

Preferably, substantially anhydrous conditions are employed.

On completion of the reaction, the desired product may be recovered in any suitable manner, as by fractional distillation, extraction with selective solvents, or other applicable procedures. Any unreacted starting materials may be employed in the preparation of further quantities of the desired product. Both batchwise and continuous processes are operable in the preparation of the present novel products.

The ethers provided by this invention are generally stable liquid materials. They may be employed for a Wide variety of agricultural and industrial purposes. Thus, for example, the ethers derived from long-chain alkynyl alcohols may be used as surfactive agents. The ethers containing a terminal acetylenic hydrogen atom may be used as hypnotics. The cyclic ethers prepared by the process of the invention are also useful as modifying and processing reagents in the textile industry. The compounds of the invention are additionally biological toxicants and may be used, e.g., as pharmaceuticals and as agricultural pesticides, e.g., as nematocides, molluscacides, insecticides, etc. The l-alkynylcyclohexyl ethers are especially effective as herbicides. The t-alkynyl ethersare particularly useful as fungicides.

The invention is illustrated but not limited by the following examples:

Example 1 This invention illustrates the preparation of a t-alkynyloxytetrahydropyran.

2-methyl-3-butyn-2-ol (34 g., 0.40 mole) containing a few drops of concentrated hydrochloric acid was gradually mixed with 34 g. (0.40 mole) of 3,4-dihydro-2H- pyran. The reaction was strongly exothermic. The mixture was allowed to stand with occasional shaking for several hours. There was then added to the reaction mixture 2 g. of sodium hydroxide and the mixture was shaken vigorously. After this, the reaction mixture was distilled. Eight grams of the carbinol were recovered, and there were obtained 54 g. of 2-(1,1-dirnethylpropynyloxy)tetrahydropyran, B. -9Z C./ 17 mm., analyzing as follows:

Percent Found Cal d. for

Example 2 This example illustrates the addition of a tertiary alkynyl alcohol to an alkoxyalkyldihydropyran.

Utilizing the procedure of Example 1, 34 g. (0.40 mole) of 2-methyl-3-butyn-2ol were reacted with 57 g. (0.40 mole) of 2-methoxy-3-ethyl-3,4-dihydro-2H-pyran, to give 45 g. of 6-(1,1-dimethylpropynyloxy)-3-ethyl-2- methoxytetrahydropyran, B. 122126 C../17 mm., the identification of which was confirmed by the following analysis:

Percent Found Cal d. for

Example 3 By the procedure of Example 1, 34.6 g. (0.25 mole) of 1-ethynyl-4-rnethylcyclohexanol were reacted with 21 g. (0.25 mole) of 3,4-dihydro-2H-pyran to give 29 g. of 2 (1 ethynyl 4 methylcyclohexyloxy)tetrahydropyran, B. l35-140 C./17 mm, 11 1.4718. The reaction was slightly exothermic.

Example 5 Similarly, by the reaction of 28 g. (0.20 mole) of 1- (l-propynyl)cyclohexanol with 17 g. (0.20 mole) of 3,4-dihydro-2H-pyran, there is obtained 2-(1-propynyl)- cyclohexyloxy)tetrahydropyran, B. ll0-115 C./l0 mm, 11 1.4793.

Example 6 Similarly, by the reaction of 1,1-diphenylpropargyl alcohol with 3,4-dihydro-2H-pyran-Z-carboxaldehyde, there is obtained 6 (1,1 diphenylpropynyloxy)tetrahydropyran-Z-carboxaldehyde.

Example 7 This example illustrates the herbicidal effectiveness of the present ethers.

Aluminum pan flats were filled with mixtures of twothirds one-quarter mesh sieved soil, and one-third sand. Over one-third of the soil surface of each pan were scattered 20 seeds each of different kinds of grasses; seeds of broadleaf plants were randomly scattered over the remaining surface. The seeds were then covered with soil to the pan top and the pan was sprayed with an aqueous solution of fertilizer and an insecticide. The surfaces of the boxes were next sprayed with 30 cc. of an acetone solution of the test chemicals, containing the chemicals at a rate equal to 25 lbs. per acre. Then the pans were placed in water and allowed to absorb moisture until the soil surface Was completely moist, after which they were held in a greenhouse under standard conditions of moisture and sunlight. After ten days, the number and species of plants which had germinated and grown were observed. The results are summarized in the following table wherein O=no phytotoxicity, i.e., germination equivalent to that usually obtained from the species of seed without application of a test chemical. The rating 3 corresponds to substantially complete suppression of plant germination and growth. The test chemicals utilized were as follows:

I. 2-(t-amyloxy)tetrahydropyran II. 2- 2-propynyloxy tetrahydropyran III. 2-( l -ethynylcyclohexyloxy)tetrahydropyran Furthermore, in tests wherein 2-(l-ethynyl-4-methyl- Example 8 This example illustrates the evaluation of the t-alkynyl ethers of the invention as fungicides.

In the procedure of this test, Bonnie Best variety tomato plants are immersed in an aqueous emulsion of the test chemical for 48 hours. Then the roots of these tomato plants, plus a control plant which has not been treated with the test chemical, are washed and about one-third of the root system in each plant is torn off. The remaining roots on each plant are immersed in a suspension of Fusarium oxysporum s. lycopersici (the organism causing tomato Wilt disease) for thirty seconds. The plants are then repotted and kept in a greenhouse. When the control plant, the tomato plant which has not been watered with a test chemical solution, shows marked disease symptoms, the plants are visually examined and then uprooted and submitted to examination of the vascular bundles of the roots to determine the extent of disease control obtained.

Z-t-Amyloxytetrahydropyran, B. 90-92 C./ 18 mm., 21 1.4340, was prepared by the reaction of 33.2 g. of 3,4-dihydro-2H-pyran with 35.3 g. of t-amyl alcohol; yield, 48.5 g. (71%). Emulsions were prepared of the 2-(1,1-dimethylpropynyloxy)-tetrahydropyran of Example l and of 2-t-amyloxytetrahydropyran, by mixing 100 ml. of each of the ethers with one ml. of Tween 20, a commercial emulsifying agent reputed to be a sorbitan monolaurate polyethylene oxide condensate. The solutions were then diluted with water to prepare emulsions containing 10 parts per million of the test chemicals.

Potted two-week old tomato plants were immersed in solutions of the test chemicals for 48 hours. After this, they were removed, the root systems washed and partially torn off, the plant roots immersed in suspensions of the tomato wilt disease organism, and the plants potted in sterile soil. A triple replication of the test was made for each of the chemicals. At the end of the growing period, when the control plant which had not received chemical treatment was dead, the plants which had been treated with the t-amyloxytetrahydropyran and dimethyl- IV. 2-(1-(l-propynyl)cyclohexyloxy)tetrahydropyran propynyloxytetrahydropyran ethers were examined. It

Grasses Brondleaf Rate, Compound 1115.]

acre Wild Bronte Rye Fox- Corn Buck- Mus- Red Sugar Cotton Oat grass grass tail wheat tard clover beet 2-(t-Amyloxyfiotrahydropyran I. 25 0 0 0 0 0 0 0 0 0 0 2- (2- Propynyloxy) tetrahydropyran 25 0 0 0 0 0 0 0 0 0 0 2 (1 ethynylcyclohexyloxy)tetrahydropyran 25 0 2 0 1 0 2 3 3 3 2-(1- (1 propynyl) -eycl0hexyloxy)- tetrahydropyran 25 1 2 1 1 0 3 3 3 3 a Stunted-1, 3 normal size.

Stunted-1/5 normal size.

Emergence delayed and incomplete.

The above data illustrate the selective phytotoxicity of the present alkynylcycloalkyloxytetrahydropyran ethers as preernergent herbicides. It will be seen from the data in the table that, whereas neither the primary alkynyloxytetrahydropyran, 2- Z-propynyloxy tetrahydropyran (II), nor the 2-t-alkoxytetrahydropyran, 2-(2-t-amyloxy)tetrahydropyran (I), is phytotoxic to grass or to broadleaf species, the alkynylcycloalkyloxytetrahydropyrans of the invention are highly toxic and effective in suppressing emergence and growth of broadleaf plants; they are also to some extent toxic to grasses, though less so than to the broadleaf species.

tive agricultural fungicides, since the acetylenic unsaturation confers properties absent in the otherwise identical saturated compound.

For the application of the present compounds as agricultural pesticides, i.e., as herbicides or fungicides, they may be applied directly to the desired substrate. However, because of the highly effective action of the present compounds, only very low concentrations need be utilized to obtain good results, and to insure even distribution of the relatively small amounts required, they are preferably incorporated with a carrier. Suitable carriers include, e.g., solid pulverulent materials such as talc, clay, pumice, or bentonite, etc. Another convenient method of formulating the present compounds for application to surfaces consists of spraying a solution or emulsion of the ether onto the surface. Liquid sprays suitable for application in this way may be prepared by dissolving the ether in an organic solvent such as a petroleum solvent, e.g., naphtha; the expenditures of large volumes of organic solvents may, however, be avoided, if desired, by extending a concentrated solution of the present ethers in an organic solvent by addition of an emulsifying agent and then Water, to prepare an oil-in-water emulsion of the ether. As emulsifying agents for such purposes may be used any of the common surface-active emulsion adjuvants, e.g., alkylbenzenesulfonates, long-chain polyalkylene glycols, salts of sulfated fatty acid amides, etc. Surface-active agents may also be used to produce a temporary suspension or dispersion of the present ethers in water without the intervention of an organic solvent, if desired. Oilin-water emulsions of the present compounds, which may be readily prepared to contain low concentrations, e.g., from 0.1% to 2% of active ingredient by weight, are, however, a particularly convenient form for use in applying the present ethers in the small concentrations required.

The alkynylcycloalkyloxytetrahydropyrans, as illustrated above, are particularly effective as selective preemergent herbicides. For this purpose, they may be applied to soil or other growth media at a rate, e.g., of about from 5 to 50 lbs. per acre. Generally, rates of from 5 to 25 lbs. per acre are effective in producing substantially complete chemical control of all broadleaf weeds. In addition to selective weeding of crops, the present compounds may be employed for eradication of undesired foliage in other locations, e.g., in areas adjacent to irrigation and drainage canals, in nursery gardens and flower beds, etc. If desired, they may be applied to soil in conjunction with other agricultural compositions, e.g., with herbicides having a more pronounced effect on grassy weeds, so that the combined result produces wide spectrum phytotoxic effect.

The new esters, furthermore, may be applied as foliage applications for the eradication of established vegetation. The rates necessary vary, for example, from 5 to 50 lbs. per acre, depending on the herbicidal activity of the active ingredient and the manner of application, the Weeds which are sought to destroy, etc. Typical rates Will be on the order of from 5 to 50 lbs. per acre.

For the application of the present compounds as agricultural fungicides, compositions as described above are preferably employed, wherein the effective ingredient is diluted by inert carrier to obtain adequate distribution of the active ingredient. The ethers or the compositions containing the ethers may be applied to the plants themselves, or to the soil in which the plants which have contracted or may be exposed to the fungus disease are growing. It is to be understood that subphytotoxic amounts of the ethers will be employed in this application. The effective concentration for fungicidal application depends on the amount and type of emulsifying agent used, the active fungicidal ether utilized, the manner of application, etc., and can readily be adjusted and concentrations selected for particular applications by those skilled in the art.

What is claimed is:

1. The process of destroying undesired plants which comprises exposing said plants to a toxic quantity of a. tetrahydropyranyl ether of the formula Where R is a lower alkynyl radical, R and R" taken together with the carbon atom to which they are attached represent the carbon atoms necessary to complete a cycloaliphatic nucleus having from 5 to 7 carbon atoms in the cycloaliphatic ring and containing a total of from 5 to 10 carbon atoms, any substituents on the said cycloaliphatic nucleus being alkyl substituents, R is selected from the class consisting of hydrogen and lower alkyl radicals, and B is selected from the class consisting of hydrogen, the carboxaldehyde radical, lower alkyl radicals, and lower alkoxy radicals.

2. The method of suppressing the growth of undesirable plants which comprises applying to soil containing seeds of said plants a phytotoxic amount of a 2-(1- alkynylcycloalkyloxy)tetrahydropyran of the formula oad l H2 wherein R represents a lower alkynyl radical and R' and R" taken together with the carbon atom to which they are attached represent a cyclohexyl nucleus carrying no substituents replacing hydrogen atoms other than lower alkyl radicals and containing a total of from 6 to 10 carbon atoms.

3. The method of claim 2 wherein said tetrahydropyranyl ether is 2-(l-ethynylcyclohexyloxy)tetrahydropyran.

4. The method of claim 2 wherein said tetrahydropyranyl ether is 2-(1-( l-propynyl)-cyclohexyloxy)tetrahydropyran. I

5. The method of claim 2 wherein said tetrahydropyranyl ether is 2-(1-ethyl-4-methylcyclohexyloxy)tetrahydropyrau.

References Cited in the file of this patent UNITED STATES PATENTS 2,574,444 Whetstone Nov. 6, 1951 2,916,501 Robertson Dec. 8, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,018 175 January 23, 1962 Margaret D, Cameron It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 10, line 57', for "-ethyl-" read ethynyl- Signed and sealed this 15th day of January l963.,=

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents 

1. THE PROCESS OF DESTROYING UNDESIRED PLANTS WHICH COMPRISES EXPOSING SAID PLANTS TO A TOXIC QUANTITY OF A TETRAHYDROPYRANYL ETHER OF THE FORMULA 